Indicating device



June 9, 1931. MOULTQN 1,809,637

INDICATING DEVICE Filed D60. 3, 1927 7% ui FEE;

0 0 5+ i INVENT A.B.MOUL 1) A ORNEY Patented June 9, 1931 ALFRED B.MOULTON, OF RIVERI-IEAD, NEVJ' YORK, ASSIGNOB T0 RADIO CORPORATION OFAMERICA, A CORPORATION OF DELAWARE INDIOATING DEVICE This inventionrelates to radio apparatus and particularly to indicating devices,adapted to denote the failure of any part of the radio apparatus inwhich it is installed.

In radio apparatus and especially in pushpull stages which are operatingunder a coinparatively light load it often happens that one tube or thecircuit associated therewith gives out, and as the remaining tube andits circuit will carry the load the stage may be allowed to operateinefiiciently for some time lpefore the operator becomes aware of thedeect.

Push-pull circuits which are operating at maximum load must beconstantly watched by an operator because if one tube or its circuitshould fail unless the defective part is promptly replaced the remainingtube or circuit will be injured by overloading.

The primary object of this invention is to provide a simple but novelindicating device which will instantly indicate the failure of a tube orpart of the circuit with which it is associated, so that whether thestage is under heavy or light load it can be kept in operation atmaximum efliciency without being constantly watched by the operator.

Another object of this invention is to provide a novel though simpleapparatus which will ring a bell or light a danger lamp when the circuitin which it is installed fails.

A further object of this invention is to provide an indicating devicewhich can be readily adapted to control push-pull stages now in usewithout materially altering the arrangement thereof.

Preferably to accomplish these objects I utilize the differential directcurrent which will be caused to flow in the output circuit of apush-pull stage on the failure of a tube thereof, to close a circuit andthereby operate a bell, danger lamp or other signalling device.

Other objects and advantages will be in part indicated in the followingdescription and in part rendered apparent therefrom when read inconnection with the annexed drawings in which:

Fig. 1 shows a circuit arrangement of the signalling device, while Figs.2 and 3 each show a modification of Fig. 1.

In the drawings in which like letters indicate like parts, T and T arethe vacuum tubes of a push-pull stage. L and L respectively are theprimary and secondary windings of the coupling transformer in the platecircuit of tubes T and T The output of secondary winding L may beutilized in any known manner.

Referring in particular to Figure 1 of the drawings the plate circuit ofT is composed of a winding 1, and half of the primary winding L. Thewinding 1 is shunted by a radio frequency bypass condenser C. The platecircuit of T is composed of a winding 1 and the remaining half of theprimary winding L. The winding 1 is shunted by aradio frequency bypasscondenser G Both of these circuits are completed through a source ofhigh potential not shown and the output elements of tubes T and Trespectively. A contact armature V is fixed between the windings 1 and 1The armature V forms part of a circuit which is completed under certainconditions through one of the contact points A or B. X is a danger lamp,hell or other signalling device that is operated when the armaturecircuit is completed. The signalling device X may be located adjacentthe apparatus to be controlled or at a point remotev therefrom, thelocation thereof depending on the convenience of the station operator.

Assuming that the stage is in operation, if

the tube T or its circuit should give out there would be a differentialdirect current flowing in the output circuit of the stage, that is therewould be no current in 1 and L while there would be current flowing in 1L. The armature V actuated by the winding 1 would close the circuit ofthe indicating device through one of thecontact points A or B. Theindicating device would be actuated thereby and the operators attentionwould be instantly called to the defect in the circuit.

The apparatus and operation of the modification shown in Figure 2 issimilar to that of Fig. 1, except that the windings for controlling thearmature 'V are at the low potential end of the primary windings L ofthe ent preferred form of my invention it will be understood that I donot limit myself thereby except as marked out in the following claims:

1. In radio apparatus comprising a push pull stage having a pair ofvacuum tubes, an output circuit connected to the output elements of eachof said tubes including a capacity shunted winding, an output winding inseries therewith and a source of high potential common to both of saidcircuits, an armature associated with said capacity shunted windings,contacts associated with said armature, a circuit including a source ofpower connecting said contacts and armature, and a signalling deviceactuated by said last named circuit when closed.

2. In radio apparatus comprising a push pull stage having a pair ofvacuum tubes, an output circuit including a capacity shunted windingconnected to the output elements of each of said tubes, an armatureadapted to be actuated by one of said windings, on the failure of thetube in circuit with the other of said windings, a pair of contacts, acircuit including a source of power connecting said armature to saidcontacts and adapted to be closed by said armature when actuated by saidwinding, and a signalling device adapted to be actuated when said lastnamed circuit is closed.

3. In relay apparatus utilizing a pair of vacuum tubes,.an outputcircuit including an inductance, a winding connecting each tere Ininalof said inductance to the anode of one of said tubes, and meansassociated with said windings to actuate an indicating de vice on thefailure of either of said tubes.

4. In apparatus including a thermionic tube, an output circuit includingan inductance connected between the anode and cathode of said tube, awinding connecting one terminal of said inductance to said anode, saidwinding being in shunt with a portion of said output circuit, anarmature associated with said winding and a signalling circuit.including a power source and an alarm adapted to be actuated on thefailure of said'tube.

5. A signalling device to be used with re lay apparatus utilizingthermionic tubes in push-pull relation comprising an alternating currentoutput circuit connected between the anodes of said tubes, a pair ofwindings, a connection between one terminal of each of said windings andthe anode of one of said tubes, a connection between the other terminalof each of said windings and a point on said output circuit, an armatureassociated with said windings and a signalling device including acircuit adapted to be closed by said armature when either of said outputcircuits fail.

A. B. MOU'LTON.

